Abrasive articles have long been used in industry for abrading, grinding, and polishing applications. They can be obtained in a variety of converted forms, such as belts, discs, sheets, and the like, in many different sizes.
Generally, when using abrasives articles in the form of "sheet goods", i.e. discs and sheets, a back-up pad is used to mount or attach the abrasive article to the abrading tool. Back-up pads are well known in the abrasive art and are described, for example, in U.S. Pat. No. 5,692,949 (Sheffield et al.) and PCT publication WO 97/20662 (Keipert), published on Jun. 12, 1997. Known back-up pads usually have one side on which an abrasive article, such as a disc, is attached. The other side of the back-up pad generally has a screw or other fastener extending therefrom to attach the back-up pad to a power tool.
Two common methods of attaching abrasive discs and sheets to back-up pads include pressure sensitive adhesives and hook and loop fasteners. When the attachment means is a hook and loop system, the abrasive article will have either loop or the hook component on the backing surface opposite the abrasive coating, and the back-up pad will have the complementary mating component, i.e., the hook loop. An example of abrasives with a hook and loop fastener is available from Minnesota Mining and Manufacturing of St. Paul, Minn. under the trade designation "Hookit" or "Hookit II." When the attachment means is a pressure sensitive adhesive, the abrasive article will generally have the adhesive thereon and the back-up pad will typically have a smooth surface such as vinyl or rubber. An example of abrasives with a pressure sensitive adhesive attachment means is available under the trade designation "Stikit" from Minnesota Mining and Manufacturing of St. Paul, Minn.
Back-up pads having dust collection grooves and dust collection holes are well known in the abrasive art and are described, for example, in U.S. Pat. No. 4,184,291, U.S. Pat. No. 4,779,385, and U.S. Pat. No. 4,759,155. Known back-up pads usually have dust collection grooves in the support surface of the back-up pad and include dust collection holes through the support surface which are in fluid communication with the dust collection grooves. The dust collection holes are typically connected to a vacuum source. The dust collection grooves and holes provide a passageway for removing dust, debris, or abrading fluid, such as water or oil, from the abrading surface.
Profile back-up pads are well known in the abrasive art. Known profile pads have contoured shaped support surfaces adapted to conform to the irregular surface of a work piece, such as wood trim or molding. However, such profile pads do not include dust holes or dust collection grooves for removing any dust, debris, or abrading fluid, such as water or oil, from the abrading surface.
In conventional back-up pads having dust grooves in their support surfaces, the engagement component attached to the support surface is two separate pieces. The first piece of the engagement component covers the central portion of the back-up pad up to the dust collection groove. The second piece of the engagement component covers the outer portion of the back-up pad extending between the dust collection groove and the outer edge of the back-up pad. When abrasive sheets are repeatedly attached and detached from the engagement component, the first piece and second piece of the conventional engagement component experience a high unit tension along the peripheral edges of the first piece and the second piece. The high unit stress is due to the force of detaching the abrasive sheet from the small area along the peripheral edges of the conventional engagement component. The high unit stress along the peripheral edges has a tendency to cause the first piece and second piece of the engagement component to delaminate from the support surface. Additionally, the conventional back-up pad includes sharp edges between the dust groove and the support surface because the dust groove is usually cut into the engagement component and support surface of the back-up pad after the backup-pad is formed. The sharp edges of the conventional engagement component also have a tendency to delaminate from the support surface of the back-up pad.